This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A235578 #25 Feb 09 2021 02:40:27
%S A235578 49,99,125,243,244,343,351,424,476,549,604,725,775,845,846,847,1025,
%T A235578 1251,1275,1324,1376,1421,1449,1520,1665,1675,1681,1682,1683,1849,
%U A235578 1863,1925,2008,2024,2057,2107,2151,2224,2276,2349,2367,2524,2528,2575,2645,2825
%N A235578 Squareful numbers with squareful neighbors.
%H A235578 Amiram Eldar, <a href="/A235578/b235578.txt">Table of n, a(n) for n = 1..10000</a>
%F A235578 a(n) = A070258(n) + 1. - _Amiram Eldar_, Feb 09 2021
%e A235578 243 is in the sequence because 242 = 2 * 11^2, 243 = 3^5, 244 = 2^2 * 61.
%e A235578 244 is also in the sequence because 245 = 5 * 7^2.
%e A235578 But 245 is not in the sequence because 246 = 2 * 3 * 41.
%t A235578 Select[Range@3051, And @@ Not /@ SquareFreeQ /@ {#-1, #, #+1} &] (* _Giovanni Resta_, Jan 12 2014 *)
%t A235578 Select[Range[2000], Union[MoebiusMu[{# - 1, #, # + 1}]] == {0} &] (* _Alonso del Arte_, Jan 12 2014 *)
%o A235578 (PARI) isok(n) = !issquarefree(n) && !issquarefree(n-1) && !issquarefree(n+1); \\ _Michel Marcus_, Jan 12 2014
%Y A235578 Subsequence of A013929.
%Y A235578 Cf. A001694, A070258, A228649 (squarefree numbers with squarefree neighbors).
%K A235578 nonn
%O A235578 1,1
%A A235578 _Juri-Stepan Gerasimov_, Jan 12 2014
%E A235578 Terms corrected by _Michel Marcus_, Jan 12 2014